MRI apparatuses include those of a type using one pair of opposingly disposed static magnetic field generating sources, in which a uniform static magnetic field region is formed in the space between the pair of static magnetic field generating sources. An imaging portion of a subject is disposed in this uniform static magnetic field region and imaged. An MRI apparatus using opposingly disposed static magnetic field generating sources has advantages that it can give open feeling to a subject, and the subject is more easily accessed by an operator compared with an MRI apparatus of a type using a cylindrical static magnetic field generating source. As the static magnetic field generating source, a permanent magnet, resistive type magnet or superconducting magnet is generally used.
A gradient magnetic field generating coil and a high frequency magnetic field generating coil are disposed on the surface on the imaging region side of each of the pair of static magnetic field generating sources. Because a pulse current flows in the gradient magnetic field generating coil in accordance with an imaging pulse sequence, it generates vibration due to the Lorentz force. Therefore, there is a problem that this vibration is transmitted from the body of the gradient magnetic field generating coil via cables thereof to the static magnetic field generating source, and thus the static magnetic field generating source vibrates.
Japanese Patent Unexamined Publication (KOKAI) No. 2002-52004 discloses a structure in which a gradient magnetic field coil is supported by a supporting system disposed through a hole provided at the center of a static magnetic field generating source. This supporting system is not in contact with the static magnetic field generating source, and is mechanically separated form a supporting system of the static magnetic field generating source. Transmission of vibration generated by the gradient magnetic field generating coil to the static magnetic field generating source is thereby suppressed.
However, in the configuration described in Japanese Patent Unexamined Publication (KOKAI) No. 2002-52004 mentioned above, the gradient magnetic field coil is supported by the supporting system at the central part thereof, and therefore the gradient magnetic field coil is likely to deform and also generate vibration. For this reason, it becomes difficult to improve the performances of the gradient magnetic field coil (for example, linearity of the gradient magnetic field, low vibration property of the gradient magnetic field coil etc.). Moreover, vibration is generated also in cables connected in order to supply a current to the gradient magnetic field coil, and reduction of this vibration is not taken into consideration. Furthermore, how to draw cables for supplying a current to the gradient magnetic field coil and piping for circulating cooling water to the outside is not taken into consideration, either.